MONTPELIER — Witnesses ranging from former Gov. Madeleine Kunin to Vermont’s current health commissioner, Dr. Harry Chen, are scheduled to testify to a state Senate committee about legislation that would allow physicians to help terminally ill patients end their own lives.Four days of testimony in the Senate Health and Welfare Committee will be punctuated Tuesday evening with a joint public hearing before that panel and the Judiciary Committee on the issue. The session is set for 5-7 p.m. Tuesday in the main House chamber of the Statehouse.Health and Welfare Committee Chairwoman Sen. Claire Ayer says she hopes her panel will vote favorably on the bill by Friday.It would then go to the Judiciary Committee, where Chairman Richard Sears has said he opposes it but won’t try to block it.